The present invention relates generally to warning lamps, more particularly to a light emitting diode (LED) warning lamp, and, even more particularly, to an LED warning lamp for a vehicle which emits light in a 360xc2x0 arc.
The Society of Automotive Engineers (SAE) publishes many new, revised, and reaffirmed standards each year in three categories, including Ground Vehicle Standards (J-Reports). Information on these standards is available on the World Wide Web at http://www.sae.org.
Two of these SAE standards are relevant to this invention. SAE J1318 pertains to gaseous discharge warning lamps for authorized emergency, maintenance, and service vehicles. The standard defines a 360xc2x0 warning lamp as a lamp that projects a light in a horizontal 360xc2x0 arc. The lamp appears to project a regularly repeating pattern of flashes to an observer positioned at a fixed location. The function of a 360xc2x0 warning lamp is to inform other highway users to stop, to yield right-of-way, or to indicate the existence of a hazardous situation. The J1318 standard defines three different classes of warning lamps, (Classes 1, 2 and 3), and specifies different photometric requirements for each class. Reprinted herebelow are the photometric requirements, for a Class 3 warning lamp as recited in Tables 3 and 7, respectively, of J1318. (All candela-second measurements are to be made by sensors placed at least 18 meters from the source).
SAE J845 is written specifically for 360xc2x0 warning lamps of any light source. This standard restates the requirements for 360xc2x0 lamps from J1318, but also provides standards for rotating signal devices, oscillating signal devices, and flashing signal devices. The devices are classified according to intended use. Reprinted herebelow are the photometric requirements for a Class 3 warning lamp, as recited in Tables 3 and 6, respectively, of J845:
Both SAE Standards J1318 and J845 are incorporated herein by reference.
Heretofore, lamps which meet J1318 requirements have generally been gas discharge lamps (e.g., Xenon lamps). Lamps which meet J845 requirements have traditionally been gas discharge or incandescent lamps, although the standard is not so limited. Xenon lamps are disadvantageous in that they require high operating voltage, are susceptible to vibration, and have limited life spans. Incandescent lamps suffer from similar disadvantages. Also heretofore, no one has been able to satisfy the SAE requirements with a lamp which uses light emitting diodes.
What is needed, then, is a light assembly comprising LEDs which meets the requirements of SAE J1318 and J845.
The present invention is a light emitting diode lamp for a vehicle which meets the photometric requirements of Society of Automotive Engineers Standards J1318 and J845. The lamp comprises a housing, a printed circuit board secured within the housing, a plurality of light emitting diodes mounted to the printed circuit board and operatively arranged to produce light in a substantially 360xc2x0 arc surrounding the housing in a horizontal plane.
Various embodiments of the invention are disclosed, and all meet selected SAE standards.
A primary object of the invention is to provide a light emitting diode warning lamp which meets SAE standards.
A secondary object of the invention is to provide a warning lamp which is more vibration resistant and less prone to failure than either incandescent or gas discharge lamps.
Another object of the invention is to provide a light emitting diode warning lamp which is more efficient to operate than either an incandescent or a gas discharge lamp.